Ion implantation is a standard technique for introducing conductivity-altering impurities into a workpiece. A desired impurity material is ionized in an ion source, the ions are accelerated to form an ion beam of prescribed energy, and the ion beam is directed at the surface of the workpiece. The energetic ions in the ion beam penetrate into the bulk of the workpiece material and are embedded into the crystalline lattice of the workpiece material to form a region of desired conductivity.
Solar cells are one example of a workpiece. Lower production costs for high-performance solar cells or any efficiency improvement to high-performance solar cells would have a positive impact on the implementation of solar cells worldwide. This will enable the wider availability of a clean energy technology. Ion implantation is one way to improve efficiency of solar cells. Solar cells or other workpieces may be loaded into a carrier after processing in an ion implanter or other piece of processing equipment.
Loading workpieces, such as solar cells, into a carrier from an ion implanter or other piece of processing equipment may have multiple drawbacks. The solar cell industry does not have well-defined standards for sizing or tolerances of solar cell workpieces or the carriers that transport these workpieces. There may be a wide variation in alignment and clearances between the workpieces and the carriers due to the lack of standardization. This also may lead to problems when loading workpieces into the carriers. Differences in workpiece sizes or carrier dimensions may result in improperly-loaded workpieces or even workpiece breakage during loading.
Besides the lack of well-defined standards, workpiece loading into carriers may be affected by machine setup, calibration, alignment, and consistency between carriers. Manufacturer tolerances are one factor in consistency between carriers. Thus, there may be differences in dimensions of the carriers from a single manufacturer. Deformation of the carrier caused by chemical processing, other wet processing, or mechanical forces is another factor in consistency between carriers. Attempts to use carriers from multiple manufacturers in a single tool also may affect consistency between carriers because each manufacturer's carrier may have different dimensions or specifications. Loading a workpiece into a deformed carrier or into carriers from different manufacturers also may result in improperly-loaded workpieces or workpiece breakage.
If the workpieces are not loaded correctly in the carrier, then the workpieces may end up in the processing equipment or on the floor. Throughput or productivity within the facility may be affected due to missing workpieces in the carrier. Workpieces also may be broken during processing if loaded incorrectly. This increases a manufacturer's material costs. Thus, there is a need in the art for an improved alignment device or an improved alignment method for loading workpieces or, more particularly, for solar cell workpieces.